Conventional superconducting rotating machines include, for example, a superconducting rotating machine described in Japanese Unexamined Utility Model Application Publication No. 57-149690 (Patent Document 1). This superconducting rotating machine has a torque tube, a drive side shaft, an anti-drive side shaft, a cylindrical warm damper, a cylindrical slide ring, and a superconducting coil, and a portion of the torque tube defines a helium-filled container. The superconducting coil is held within the warm damper and on an outer circumferential surface of a helium-filled container defining part of the torque tube.
The drive side shaft is located on one axial end side of the helium-filled container defining part, while the anti-drive side shaft is located on the other axial end portion side of the helium-filled container defining part. The drive side shaft and the anti-drive side shaft are mechanically coupled through the warm damper.
The torque tube is fixed to the anti-drive side shaft and coupled through a spoke to the slide ring. The spoke supports the slide ring. The drive side shaft has a cylindrical part at an end portion on the superconducting coil side, and a cylindrical supporting ring is fitted into an inner circumferential surface of the cylindrical part. An outer circumferential surface of the slide ring is axially slidably fitted into an inner circumferential surface of the supporting ring.
The spoke is made of titanium, which has low thermal conductivity among metals, or titanium alloy, while the material of the supporting ring is made of graphite-containing Teflon (registered trademark) having low thermal conductivity and excellent lubricity. Therefore, sliding surfaces of the supporting ring and the slide ring are made of graphite-containing Teflon (registered trademark). This superconducting rotating machine has the slide ring made slidable against the supporting ring so that an axial thermal strain can be absorbed by a slide therebetween.